FOLIAR INVOLUCRES IN DICOTYLEDONOUS INFLORESCENCES - ORGANIZATION ANDCONSTRUCTION

A general review of involucres diversity is presented. An involucre it self is considered as ''type of construction'' which corresponds to th e numerous ''types of organization'' representing this ''type of const ruction'' in various taxa within Dicotyledonae. All the involucres for med by foliar organs are divided into two groups: a) involucres formed by non-sterile leaves and b) involucres formed by sterile ones. The s econd group proves to be a complex one because of the different nature of sterile leaves forming the involucre. These leaves may belong eith er to the floral unit or to the enrichment zone. It is clearly shown t hat involucres of any nature may demonstrate any degree of specializat ion expressing in colour, size, shape and fusion of leaves. The main f unctions of involucre i.e. defence of flower buds and attraction of po llinators may be successfully carried out by any kind of involucre. Th e corollary is that strong correlation between ''type of organization' ' and ''type of construction'' is in this case absent.